(Subfamily Byttnerioideae), Tribe Hermannieae.
Habit and leaf form. Shrubs; non-laticiferous and without coloured juice. ‘Normal’ plants. Leaves well developed. Plants with roots; non-succulent. Leaves cauline. To 0.3–0.6 m high. Self supporting, or climbing. Mesophytic. Not heterophyllous. Leaves small, or medium-sized; alternate; with blades; petiolate, or subsessile (D. monoicum). Petioles wingless. Leaves with ‘normal’ orientation; simple; not peltate. Leaf blades neither inverted nor twisted through 90 degrees; dorsiventral; entire; flat; ovate, or obovate, or oblong, or elliptic; pinnately veined; cross-venulate; oblique at the base (slightly), or rounded at the base. Mature leaf blades adaxially pubescent; abaxially pubescent. Leaves with stipules. Stipules intrapetiolar; free of the petiole; free of one another; spiny; caducous. Leaf blade margins serrate (or irregular). Leaf anatomy. Hairs present; complex hairs present. Complex hairs stellate.
Reproductive type, pollination. Fertile flowers hermaphrodite, or functionally male and functionally female (D. monoicum). Unisexual flowers present (D. monoicum), or absent. Plants hermaphrodite, or monoecious (D. monoicum). Female flowers aggregated in ‘inflorescences’, or solitary; without staminodes. Male flowers aggregated in ‘inflorescences’, or solitary. Plants homostylous.
Inflorescence and flower features. Flowers solitary, or aggregated in ‘inflorescences’; not crowded at the stem bases; axillary. Inflorescence when not solitary few-flowered. Flowers in cymes. Inflorescences simple; axillary. Flowers pedicellate, or subsessile (D. sp. B Kimberley Flora(G.J.Keighery 10138)); bracteate (D. sp. B Kimberley Flora(G.J.Keighery 10138)), or ebracteate; bracteolate, or ebracteolate (D. sp. B Kimberley Flora(G.J.Keighery 10138)); regular; neither papilionaceous or pseudo-papilionaceous; 5 merous; tetracyclic (when hermaphrodite). Perianth with distinct calyx and corolla; 10; 2 -whorled; isomerous. Calyx present; 5; 1 -whorled; gamosepalous; lobed. Calyx lobes about the same length as the tube. Calyx hairy (densely stellate or bifid hairy on outside, or sparse, or only at lobe apices); valvate; exceeded by the corolla; regular; neither appendaged nor spurred. Calyx lobes triangular (to narrowly so). Epicalyx absent. Corolla present; 5; 1 -whorled; not appendiculate; polypetalous; contorted; pink (to deeply pink or lilac), or white; persistent. Androecium present (as staminodes in D. monoicum). Fertile stamens present, or absent (D. monoicum). Androecial members definite in number. Androecium 5. Androecial members adnate (in D. sp. B Kimberley Flora(G.J.Keighery 10138)), or free of the perianth; free of the gynoecium; all equal; coherent (into tube at least at the base); 1 - adelphous; 1 -whorled. Androecium exclusively of fertile stamens. Stamens 5; all more or less similar in shape; isomerous with the perianth; filantherous. Anthers dehiscing via longitudinal slits; bilocular. Fertile gynoecium present, or absent (in male flowers of D. monoicum). Gynoecium 2 carpelled. The pistil 2 celled. Carpels reduced in number relative to the perianth. Gynoecium syncarpous; synovarious; superior. Ovary plurilocular; 2 locular; sessile. Ovary summit hairy, the hairs not confined to radiating bands. Gynoecium stylate. Styles 2; free; simple; apical; hairy. Stigmas 2; 1 - lobed. Placentation axile. Ovules 2 per locule.
Fruit and seed features. Dispersal unit the seed.
Geography, cytology, number of species. Native of Australia. Endemic to Australia. Australian states and territories: Western Australia and Northern Territory (D. monoicum), or Western Australia. Northern Botanical Province. A genus of 3 species; 3 species in Western Australia; 2 endemic to Western Australia.